Chainsets and bottom brackets are usually matched. So if you have an AC set of cranks then you need 109mm axle length(manufacturers recommendation) If its an XT then it would need a 112.5mm axle. If its a middleburn crank it will need the length of axle recommended for it and so on and so forth
Find out what axle length is required by shimano for their alivio crank and fit it. Unfortunately your thinking is that any crank fits any BB and this isnt so. Of course you could be lucky and find out the required axle length is the same but in the bike world we just aint that lucky
We could really really make this confusing for you by introducing into this formula something called the 'chainline' and we could go on further to explain in great detail and at great length the ins and outs of correctly measuring the bike its stays its cranks its BB and about 1/2 dozen other bits and nobody here knows what the f** it all means
Best stick with the makers recommended length
(tin hat at the ready Sir)
The thread stuff is just down to the headset you have fitted
Nowadays there are thousands of Ahead stuff about so swopping over is a doddle.
Call it £20 for a reasonable headset then you have the cost of a stem and thats about it.
Only thing to note is that as the threaded doesnt much stick up above the top of the tube the Ahead does. Youll need about 38mm for the headset plus any spacers you want under the stem to raise the height then the height of the steerer itself
For instance, if the headtube is 115mm youll need that +38mm[h/s]+50mm[stem] so you would require a fork with a steerer 203mm long as a minimum .Got that
1976 Raleigh Chipper,1991 Muddy Fox Adventurer,1991 Claud Butler Ventoux 400 ,1992 Raleigh Diablo ,1992 Rudy Project, 1995 Cannondale M200 ,1997 Santa Cruz Tazmon ,1997 Specialized Stumpjumper ,1997 Specialized Rockhopper ,1997 Marin Quake 9.0,1998 Marin Pallisade trail ,1998 Raleigh Torus,1999 Orange Clockwork , 2005 Kona Hahanna ,2007 On-One Inbred ,2010 Orange Pure7 And of course The Ti
The Marvellous Mechanical Hope Collection ,and other Hope niceties